At present, WLAN operates in a license-exempt frequency band of 2.4G and has been considered as important means of offloading cellular network services due to its low device cost, easiness to deploy, high data rate and other advantages. A burden on a cellular network can be effectively lowered by using the WLAN to offload webpage browsing, QQ, MSN and other low-value services among the cellular network services or by using the WLAN to offload the cellular network services when congestion occurs in the cellular network, and the WLAN can improve indoor coverage and provide an access at a high speed, to provide subscribers with better wireless network services.
However, after a mobile terminal originally served in the cellular network is handed over to the WLAN, an Access Point (AP) in the WLAN accessed by the mobile terminal may currently be heavily loaded, thus resulting in a poor network quality condition and even a congestion status of the network, and then the mobile terminal communicating in the WLAN through the AP cannot be provided with a high quality of service, so that the mobile terminal may have to be handed over back to the cellular network, thus bringing a higher burden to the cellular network and influencing an experience of the subscriber.